This invention relates to a series of acetylenic compounds, pharmaceutical compositions and methods for use thereof. More particularly, the acetylenic compounds of the present invention are nicotinamide adenine dinucleotide oxidase hydride donor inhibitors useful in treating or ameliorating inflammatory disorders.
The nicotinamide adenine dinucleotides (NAD, NADH, NADP and NADPH) are essential cofactors in all living systems and function as hydride acceptors (NAD, NADP) and hydride donors (NADH, NADPH) in biochemical redox reactions. The six-step biosynthetic pathway begins with the oxidation of aspartate to iminosuccinic acid, which is then condensed with dihydroxyacetone phosphate to give quinolinic acid. Phosphoribosylation and decarboxylation of quinolinic acid gives nicotinic acid mononucleotide. Adenylation of this mononucleotide followed by amide formation completes the biosynthesis of NAD. An additional phosphorylation gives NADP (Begley, T P., et al., The Biosynthesis of Nicotinamide Adenine Dinucleotides in Bacteria, Vitam. Horm., 2001, 61, 103–119).
The importance of reactive oxygen species (ROS) in the pathogenesis of inflammatory diseases is increasingly recognized. During inflammation, polymorphonuclear leucocytes (PMN) and macrophages become stimulated by lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF-α) as well as cytokines IFN-γ and interleukin-2 (IL-2). Stimulation results in the cellular assembly of a nicotinamide adenine dinucleotide oxidase hydride donor, in particular NADPH, a membrane bound enzyme which is the major source of ROS. The generation of ROS has been shown to be elevated up to 10 fold in patients with various inflammatory and autoimmune rheumatic diseases (R. Miesel, et al., Suppression of Inflammatory Arthritis by Simultaneous Inhibition of Nitric Oxide Synthase and NADPH Oxidase, Free Radical Biology & Medicine, 1996, 20(3), 75–81).
Two known inhibitors of NADPH Oxidase, diphenylene iodoniumchloride (DPI) and staurosporine have been shown to have antiinflammatory effects in mice with potassium peroxochromate arthritis. Daily doses of 2.8 μmol/kg of DPI and 30 nmol/kg staurosporine inhibited the arthritis by 50%. Complete inhibition was obtained with 10 mmol/kg DPI while 85% inhibition of the arthritis was achieved with 100 nmol staurosporine (R. Miesel, et al., Antiinflammatory Effects of NADPH Oxidase Inhibitors, Inflammation, 1995,19(3), 347–362).
The antirheumatic drug Piroxicam has been shown to reduce levels of ROS in human patients with rheumatoid arthritis and osteoarthritis by 25% at pharmacological doses. In vitro studies showed that this inhibition was caused by interference of the activation of NADPH Oxidase (P. Biemond, et al., Superoxide Production by Polymorphonuclear Leucocytes in Rheumatoid Arthritis and Osteoarthritis: In vivo Inhibition by the Antirheumatic Drug Piroxicam Due to the Interference With the Activation of the NADPH Oxidase, Annals of the Rheumatic Diseases, 1986, 45, 249–255).
The deposition of β-amyloid in the brain is the key pathogenic event in Alzheimer's disease. Recently, β-amyloid has been shown to induce the stimulation of NADPH oxidase in human neutrophils and microglia in a dose dependent manner. The subsequent production of ROS is at least in part responsible for the neurodegenerative effects of β-amyloid (V. D. Bianca, et al., β-Amyloid Activates the O2-Forming NADPH Oxidase in Microglia, Monocytes, and Neutrophils, The Journal of Biological Chemistry, 1999, 274, 15493–15499).
Thus, there is a need for the acetylenic compounds of the present invention as nicotinamide adenine dinucleotide oxidase hydride donor inhibitors and a method for use of such compounds in treating or ameliorating a reactive oxygen species mediated inflammatory disorder.